Water quality degradation is a problem of growing proportions. One measure of water quality is the amount of gross pollution that is carried from our roads and streets into our storm water system and eventually into the reservoirs that we rely on for potable water. Our rivers, lakes, dams and ultimately the ocean are becoming the repository for gross pollution which is lowering the quality of those very important water sources.
Gross pollution in the main (90%) comprises organic matter like branches, twigs, leaves, and soil, the remainder being non-organic matter like plastic containers, bags, wrappers; paper; cans; and cigarette butts.
In one example of a storm water drainage system, storm water collected from metropolitan and township road surfaces and household roofs ends up in the underground storm water drainage system. Ground level storm water entry points called gully traps let a variety of various sizes of gross pollution into the storm water drainage system. Typical drainage systems comprise underground pipes and sometimes exposed water conduits, which carry storm water to holding reservoirs, rivers and ocean outflows.
Gross pollution is likely to accumulate in large quantities at the outflows of drainage systems and concern about the environmental impact of high concentrations of this gross pollution is justified.
Filtering of storm water using current techniques is a costly and time consuming undertaking and it is not unusual for water authorities to prefer to address the problem by cleaning up the very visible consequences of gross pollution which emits from the drainage system rather than actually reducing the contamination of the storm water system at its source. Sometimes gross pollution or filtering is undertaken at intermediate points along the drainage system but the typical approach is to install end of line grates which tend to quickly foul up and require constant maintenance and which do not deal with oil and oil like contaminates.
Similar considerations also apply to the treatment of polluted industrial water.
Some of the less than desirable features of prior and current storm water and gross pollution filters include:
use of many metal parts which require anti-rusting treatment or use of expensive stainless steel elements PA1 moving parts which require maintenance and periodic replacement, and which are liable to jam, corrode and require frequent cleaning to maintain their efficiency PA1 use of large areas adjacent the existing drainage system for providing settling reservoirs which are sometimes many times wider than the drains and conduits with which they are associated PA1 high hydraulic head loss between the inlet and outlet resulting in low filter efficiency at low and high flow rates and great disruption to the drainage layout providing unwanted restrictions and prohibitions to the retrofitting of such filters to existing drainage systems PA1 small time intervals between pollution collection are required when many small gross pollution filters are incorporated into the drainage system and further, existing shapes of pollutant collection volumes are often difficult to empty and clean PA1 in-line grate type filters for different types of pollutants require large areas to handle the some time large volumes of gross pollutants and which have a large potential for blockage as well as often requiring the manufacture of unique elements at greater cost than desirable PA1 different efficiency at different flow rates, and often the poorest efficiency occurs at both low and high flow rates PA1 blockages caused particularly by sediment build up at the inlet and outlet of the filter apparatus and the accumulation of certain types of pollutants can be a health hazard and cause unnecessary use of overflow routes which bypass the filter apparatus PA1 prior arrangements also include apertured and solid weirs which induce a back pressure along the incoming storm water pipe during and certainly after the filter arrangement becomes inefficient and unable to adequately filter the flow of incoming storm water carrying gross pollutants.
These and other problems are reduced or eliminated by the invention disclosed herein.